In preparation operations for oil exploration in deep sea wells, several production tubes coiled to each other descend from the platform. These tubes may be used to drain product or transport equipment involved in the operation up to and down from the platform. Clamps may be installed at the production tube to simultaneously anchor the production tube, an electro-hydraulic hose, and an electric cable.
The clamp anchors the electro-hydraulic hose and the electric or hydraulic cable at the production tube, with a 50 lbs·ft of torque, in order to avoid the compression of hydraulic lines, and to protect them of possible damages to the rubber lining, during the descent and ascent of the production tubes. The clamps may be inserted inside of another larger tube, whereby the external diameter of these clamps has friction with the internal diameter of the larger tube during the descent and the ascent of the production tubes. In the area between the internal diameter of the larger tube and the external diameter of the production tube, there is a chemical compound with great abrasive power, which acts as a hydrate formation inhibitor, in the area of the wellhead.
The clamps currently used present several problems during operation due to the process which involves very considerable values of potential energy and friction forces as well as chemical attack to the clamp material. All these factors acting during the operation make the clamp currently used very vulnerable to fractures and chemical attacks due to its mechanical construction. The clamp may include a blanket of vulcanized rubber in the metal with the purpose of ensuring a suitable tightness and avoiding the sliding of the clamp fitted on the tube. The clamp is tightened by means of screws and casters, with a 50 lbs·ft torque, using a pneumatic impact wrench. In the clamp used currently there are equidistant metallic plates screwed in the metal body 90 degrees apart, aimed to promote friction with the inner wall of the larger tube, protecting the metal body and, consequently, the electro-hydraulic hose and the electric cable. However, due to clamp shocks many of these wearing plates become loose, falling in the bottom of the well. Another problem is that the clamp is inflexible, being made with no ductile materials, and does not absorb small impacts that usually occur against the fixed parts of other equipment involved in the operation. This can cause the clamp to break, and metal parts to subsequently fall to the bottom of the well resulting in damage and lost time. Another problem is the heavy maintenance demands after use which require washing with fresh water under pressure, and immediately lubricating movable parts. Further, the use of metals with different characteristics being assembled to the clamp and having different electric potentials may result in a galvanic pile being formed in a marine environment.
The clamp currently used presents several problems, which makes the equipment very fragile prior to an operation involving loads with great mass and considerable mechanical demands. Therefore, an objective of the present invention is to present a improved clamp with high level of safety and very low maintenance schedule. After several studies and tests in field, a clamp has been developed wherein the whole body is made of rubber, making it unbreakable after a fall, and extremely resistant to chemical attacks in marine environments.
In an embodiment, the invention involves a clamp for simultaneously anchoring the production tube, the electro-hydraulic hose, and the electric cable for use in deep sea oil search and production operations, in the production tube column in installation and uninstalling operations of sub sea Christmas trees (ANM), and with housings to simultaneously anchor the production tube, the electro-hydraulic cable and the electric cable, while also acting to centralize the production tubes into a column. The clamp includes a pre-formed metallic belt (12) to which a first rigid metallic curve (13) is welded. The rigid metallic curve reinforces and protects the anchorage housing of an electro-hydraulic hose, which is secured by the clamp. The belt (12) further includes a second rigid metallic curve (14) to reinforce and protect the electric cable which is secured by the clamp. The belt includes rigid symmetrical forks (15) and (16) that are welded in the rotation area of screws that will tighten the clamp. The clamp includes a body made of vulcanized rubber having three tips (26), (27) and (28), which are formed at equidistant angles of 120°. The clamp body includes a larger bore hole in the center (17), a medium bore hole in half oblong form (9) within said tip (27), a small bore hole in half oblong form (8) within the second tip (26), and a bore slot (18) within the third tip (28) suitable for the opening and closing of said clamp (1). The clamp body further includes a small bore hole (10) located in one side of said slot (18), where two threaded casters (2) are set up having a smaller diameter than said hole (18) in order to make said caster (2) pivotable inside of said hole (18). In another aspect, the caster (2) is threaded with a screw (4) having a washer (3), in which a safety ring (5) is set up at the end to avoid the disassembly of the screw (4) in the counter-torque of clamp opening. In another aspect, the after welding the belt (12) curves (13) and (14), and forks (15) and (16) is complete, the rubber body of the clamp (1) is produced by vulcanization.